Lecture 12 Databases

1. Lecture 12 Databases

2. Databases Most Common Computer Application Nothing More than a Collection of Files Filing Cabinet Uses Banking Telephone Call Centers Sales Schools Customer Data Internet Searches

3. Definition Organized Library of Related Information that Can Be Stored in a Computer Not Totally True Only Data is Stored in Database Must Make Sense of Data

4. Concept Data Manipulation Data Entry Addition and Deletion of Data Data Modification Rearrangement and Viewing of Data Query Functions (Locate Data) Report Generation Printing Reports and Database Files

5. Critical Resource Maintain Unity and Harmony Common Goals and Objectives Best Decision Never Guaranteed People Make Choices Disregard Important Data Need Best Information Possible

6. Quality Information Data in the Best, Most Recognizable Form Characteristics Accurate - Free of Bias Timely - When Needed; Not Outdated Relevant- Pertaining to the Decision Decision Making without Information Chance

7. Information Systems Main Role Gathering and Processing Data Making Data More Useful Efficient Data System Filters Data Summarizing Condensing Screening Ideal System Allows User to Specify Filters

8. Benefits and Disadvantages Benefits Less Useless Data More Efficient Information System Disadvantages Less Data to Make Decisions Difficult When People Share Data Who Does the Filtering?

9. Data Management Process of Storing and Retrieving Data Tasks Describe Real-World Organization of Data Physically Store Data Retrieving Data in Meaningful Manner to Decision Maker

10. TDP Traditional Data Processing Process Oriented Data Flows from One Program to Another Good for One Specific Processing Need Not Good when Data Must Be Shared

11. Traditional File Processing

12. DBMS Database Management System Data Oriented Focus Is on the Data Database Separate from Applications Programs which Process Data Data Is a Shared Resource

13. Data Base Management System

14. Benefits of DBMS Improved Data Integration All Organizational Data in One Place Increased Accessibility of Data Everyone Has Access to All Data Improved Data Control Control Over Who Accesses Data

15. Differences

16. Functions of DBMS Define All Data and Specify Relationships Provide Methods for Modifying Database Adding, Deleting, Editing Data Protect Data Resource for Security Provide for Data Sharing Allow for Data Retrieval Step 1 Most Critical

17. Database Files Master File Transaction File Sequential File Index-Sequential File Sequential File Index File

18. Data A Representation of Real-Like Objects Known as an Entity Tangible or Intangible Entities Have Attributes Characteristic of the Entity Attributes Have Values Physical Data Representations

19. Data Manager Must Decide What Values Are Important What to Gather, What to Overlook Knowing How Data Is Represented in the Real World Is Critical to Creating an Efficient Information System

20. Example A Person Is an Entity Tangible Aspects Intangible Aspects The Physical Characteristics of the Person Attributes Have Assigned Values

21. Example Person Has a Name, Birthdate Name is SnuffySmith Born in 1932 Person Has a Family, Job Works as a Janitor at Acme Corp. This Data Represents Physical Values

22. Database Terms A Database Is a Collection of Data Files A Data File Is a Collection of Records A Record Is a Collection of Related Data A Field Is a Collection of Characters A Character Is the Physical Data Representation of the Entity

23. Database Terms A Database Contains Related Entities  A Data File Contains Like Entities  A Record Contains Data In Fields Describes a Unique Occurrence of an Entity  A Field Contains Individual Data Units  A Character Can Be Either Numeric or Alphanumeric

24. Keys Database Keys Are Essential Without Keys Cannot Locate Data Primary Key Uniquely Identifies an Occurrence of an Entity Secondary Key Identifies a Number of Records Which Share the Same Properties

25. Lecture 12 Databases